Survival and migration of photoreceptor precursors following transplantation into a macaque eye with host photoreceptors ablated

Abstract

Purpose : Non-human primates have the potential to be a highly informative model for stem cell-based vision restoration. In a new laser lesion model of macaque photoreceptor loss, we investigated donor photoreceptor survival and migration following transplantation in the subretinal space of macaque eyes.

Methods : In a 4-year-old female macaque, nine perifoveal lesions with localized damage to the photoreceptor layer were created using femtosecond pulses delivered through adaptive optics (730 nm, 55 fs, 80 MHz, 0.81° × 0.73°). Immune suppression was provided by a subcutaneous injection of cyclosporine and an oral prednisone. Fluorescently-labeled photoreceptor precursors (CRX^+/tdTomato) derived from WA09 human embryonic stem cells were transplanted subretinally, raising two blebs, one containing all nine lesions and one in a lesion-free region. Donor cells were monitored noninvasively between six days and three months post-transplantation using fluorescence (λ_Excitation: 561 nm; λ_Emission: 580-676 nm) adaptive optics scanning light ophthalmoscopy (AOSLO), SLO, and OCT (Heidelberg Spectralis). Immunohistochemical examination was then performed.

Results : We observed individual donor cells and cell clusters in both blebs. Fluorescence AOSLO imaging showed that the area of a cell cluster in the bleb with lesions decreased 25% after 4 weeks and 65% after 10 weeks. The area of cell clusters in the non-lesioned retina decreased 50% (±5%) after 4 weeks, and 80% (±7%) 10 weeks post-transplantation. In the non-lesioned retina, immunohistochemistry did not show any evidence of migration of donor cells; however, in the lesioned retina some cells migrated into the outer plexiform layer and sent processes toward the inner retina.

Conclusions : This finding suggests that laser ablation disrupts an anatomical barrier posed by the host photoreceptor layer resulting in donor cell migration toward the bipolar cell layer, an important step toward establishing functional connectivity. The progressive loss of donor cells post-transplantation remains a challenge to vision restoration. The ability of adaptive optics retinal imaging to monitor over months fluorescently-labeled donor cells at the celular scale could accelerate the development of methods to improve donor cell survival and integration.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.